CN112714802A

CN112714802A - Permanent magnet stabilizing method, magnet stabilizing permanent magnet and permanent magnet motor

Info

Publication number: CN112714802A
Application number: CN202080004861.0A
Authority: CN
Inventors: 赖彬; 王子京; 景遐明
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2021-04-27
Also published as: EP3933859B1; EP3933859A1; WO2021217544A1; EP3933859A4

Abstract

A steady magnetic permanent magnet can be applied to the fields of new energy automobiles, wind power generation, energy-saving household appliances, intelligent manufacturing and the like. The magnet-stabilizing permanent magnet comprises a magnetization direction (10) in which heavy rare earth elements are contained, the heavy rare earth elements being dispersed in the magnet-stabilizing permanent magnet and having different concentrations in a direction (40) perpendicular to the magnetization direction. When the magnetism stabilizing permanent magnet is subjected to magnetism stabilizing treatment, films with different thicknesses or films with different concentrations of heavy rare earth elements are formed on the first surface (20) of the permanent magnet substrate, so that the magnetism stabilizing permanent magnet meeting the demagnetization resisting requirements of different positions can be obtained, and the use amount of the heavy rare earth elements is saved.

Description

Permanent magnet stabilizing method, magnet stabilizing permanent magnet and permanent magnet motor

Technical Field

The application relates to the field of permanent magnet materials, in particular to a permanent magnet stabilizing method, a magnet stabilizing permanent magnet and a permanent magnet motor.

Background

The neodymium iron boron permanent magnet material is widely applied to the fields of new energy automobiles, wind power generation, energy-saving household appliances, intelligent manufacturing and the like due to excellent magnetic performance, and the development of global energy conservation, environmental protection, low carbon and other green concept economy is promoted. The new development and application put higher demands on the permanent magnetic material, in particular to a new energy automobile, and a driving motor of the new energy automobile requires the permanent magnetic material to have high remanence and maximum energy product and also requires the permanent magnetic material to have high coercive force. The permanent magnet for the vehicle contains high content of Heavy Rare Earth (HRE) elements such as dysprosium Dy, terbium Tb and the like, and has high price, so that the cost of the permanent magnet material in the permanent magnet motor is more than 30 percent.

In order to reduce the usage amount of heavy rare earth elements, the heavy rare earth diffusion technology makes a breakthrough and is widely applied in the last decade. The conventional heavy rare earth element diffusion process is to form a layer of film of heavy rare earth elements such as Dy or Tb or a compound film rich in Dy or Tb with uniform thickness on the surface of the neodymium iron boron base material by a physical or chemical method, and then to diffuse the heavy rare earth elements such as Dy or Tb from the surface of the neodymium iron boron base material to the inside of the neodymium iron boron base material along a grain boundary through high-temperature heat treatment, so that the overall coercive force of the neodymium iron boron permanent magnet is enhanced. This method requires a large amount of heavy rare earth elements to be consumed due to a large coating area.

Disclosure of Invention

The embodiment of the application provides a permanent magnet, a magnetism stabilizing permanent magnet and a permanent magnet motor, which can improve the overall coercive force of the permanent magnet by using less Heavy Rare Earth (HRE) elements.

The application provides a method for stabilizing magnetism of a permanent magnet, which comprises the following steps: providing a permanent magnet base material, wherein the permanent magnet base material comprises a plurality of surfaces and a magnetization direction, the plurality of surfaces comprise a first surface, and the first surface is vertical to the magnetization direction; providing a magnetic stabilizing material, wherein the magnetic stabilizing material contains heavy rare earth elements; processing the magnetic stabilizing material on the first surface to form a first surface film; the first surface film has different film thicknesses in a distribution along a first direction, or the first surface film has different concentrations of heavy rare earth elements in a distribution along a first direction, the first direction being a direction perpendicular to a magnetization direction; and carrying out diffusion treatment on the heavy rare earth element on the permanent magnet base material with the thin film formed on the first surface.

In the first aspect, the permanent magnet base material may be a base material made of neodymium iron boron material, the magnetic stabilizing material may be a metal simple substance, or an alloy, or may further include a slurry obtained by mixing a compound of heavy rare earth elements with an organic solvent, and the heavy rare earth elements may include elements such as dysprosium Dy or terbium Tb. The permanent magnetic substrate has a magnetization direction, the first surface is perpendicular to the magnetization direction, and for example, the magnetization direction is generally a height direction of the permanent magnetic substrate having a rectangular parallelepiped structure, and the first surface is generally an upper surface or a lower surface of the rectangular parallelepiped. Taking the permanent magnetic substrate of a cylindrical structure as an example, the magnetization direction is also the height direction, and the first surface is usually the upper surface or the lower surface of the cylindrical structure. The first direction is a direction perpendicular to the magnetization direction, and in the case of a permanent magnet base material of a rectangular parallelepiped structure, the direction perpendicular to the magnetization direction may be a longitudinal direction or a width direction of the rectangular parallelepiped. The first surface is processed to form a film, and a physical sputtering method can be adopted, such as: the heavy rare earth elements are bombarded by the target material to form a film on the first surface of the permanent magnet base material, and the slurry can also be coated on the first surface by a chemical coating method. A thin film may also be formed on the first surface by plating, electrodeposition, or the like. The diffusion treatment may be performed by placing the substrate in a vacuum furnace and performing a heat treatment at 900 degrees celsius for 16 hours. The diffusion treatment may be followed by a heat treatment at a temperature of 450 degrees celsius for 8 hours. Of course, the specific temperature and time are not limited to 900 degrees for 16 hours and 450 degrees for 8 hours, but may be other values as long as the diffusion treatment of the heavy rare earth element is completed. From the first aspect, in the process of stabilizing the magnetism of the permanent magnet, the first surface film has different film thicknesses or different concentrations of heavy rare earth elements on the first surface, so that the heavy rare earth elements in the magnetism-stabilized permanent magnet are dispersed in a direction perpendicular to the magnetization direction and have different concentrations after the film diffusion. This first aspect has just formed the film and has still saved heavy rare earth's use amount on the first face under the prerequisite of having satisfied the anti demagnetization demand of steady magnetism permanent magnet different position differentiation like this, has reduced the cost of steady magnetism permanent magnet, in addition, through the control to film thickness or heavy rare earth's concentration on the first face, can realize steady magnetism permanent magnet's customization as required.

In a possible implementation manner of the first aspect, the film thickness of the film on the first surface is first decreased and then increased from one end to the other end of the first surface along the first direction.

In this possible implementation, the concentrations of the heavy rare earth elements in the first surface thin films are generally the same, the first surface thin films have different film thicknesses, and the film thickness from one end of the first surface to the other end along the first direction decreases and then increases, and may decrease and then increase in an equal proportion or decrease and then increase in a continuous manner. The inflection point from decreasing to increasing is generally the centerline of the first face, and is understood to mean the tendency of the film thickness to decrease in a gradient from one end of the first face to the centerline and to increase in a gradient from the centerline to the other end. The coercive force corresponds to the concentration of the heavy rare earth element, and the two sides are large and the middle is small, so that the requirements of large demagnetization resistance at the edges and small demagnetization resistance at the center of the steady magnetic permanent magnet can be met.

In a possible implementation manner of the first aspect, the concentration of the heavy rare earth element of the thin film on the first surface is first decreased and then increased from one end to the other end of the first surface along the first direction.

In this possible implementation, the film thickness of the first surface film may be the same, but the concentrations of the heavy rare earth elements in different regions of the first surface film are not all the same, and the concentration of the heavy rare earth element in the first surface film is decreased first and then increased, and may be decreased in an equal proportion and then increased in a gradient, or may be decreased continuously and then increased. The inflection point from the lowering to the rising is generally a centerline of the first face, and it is understood that the concentration of the heavy rare earth element is a tendency of decreasing in a gradient from one end of the first face to the centerline, and the concentration of the heavy rare earth element is a tendency of increasing in a gradient from the centerline to the other end. The coercive force corresponds to the concentration of the heavy rare earth element, and the two sides are large and the middle is small, so that the requirements of large demagnetization resistance at the edges and small demagnetization resistance at the center of the steady magnetic permanent magnet can be met.

In a possible implementation manner of the first aspect, on the first surface, the first surface thin film is divided into a plurality of thin film regions according to the film thickness or the concentration of the heavy rare earth element, wherein the film thicknesses of the plurality of thin film regions are different, or the concentrations of the heavy rare earth element of the plurality of thin film regions are different.

In this possible implementation, the thin film on the first side may include a plurality of thin film regions, which may be continuous or discontinuous, and the thin film thickness of different thin film regions is different, or the concentration of the heavy rare earth element of different thin film regions is different. In this possible implementation, the variation of the film thickness or the variation of the concentration of the heavy rare earth element can be easily controlled by the film area.

In a possible implementation manner of the first aspect, along the first direction, the thickness of the middle portion of the first surface thin film is lower than that of the two end regions, or the concentration of the heavy rare earth element in the middle portion is lower than that of the two end regions.

In a possible implementation manner of the first aspect, the plurality of surfaces further include a second surface, the second surface is perpendicular to the magnetization direction, and the second surface and the first surface are respectively located on two opposite sides of the permanent magnet substrate, and the magnetic stabilization method further includes: and processing the magnetic stabilizing material on the second surface to form a second surface film, wherein the second surface film has different film thicknesses in the distribution along the first direction, or the second surface film has different concentrations of heavy rare earth elements in the distribution along the first direction, and performing diffusion processing on the heavy rare earth elements on the permanent magnet base material after the film is formed on the second surface.

In this possible implementation, the first and second surfaces perpendicular to the magnetization direction are opposite surfaces that are located on opposite sides of the permanent magnetic substrate, and the first and second surfaces are also generally two parallel surfaces that are parallel to each other. Taking the example of a permanent magnetic substrate of rectangular parallelepiped configuration, the first and second faces are typically the upper and lower faces of the rectangular parallelepiped. Taking the permanent magnetic substrate of a pancake cylindrical structure as an example, the first and second faces are generally the upper and lower surfaces of the pancake cylindrical body. The process of forming a thin film on the second face and the diffusion treatment can be understood with reference to the process of forming a thin film on the first face and the first face thin film diffusion treatment in the above-described first aspect. According to the possible implementation mode, the thin films are formed on the first surface and the second surface, so that the inside of the magnetism-stabilizing permanent magnet obtained through the permanent magnet base material with larger thickness can contain heavy rare earth elements.

In a possible implementation manner of the first aspect, the steps include: processing the magnetic stabilizing material on the second side to form a second side film comprises: and after the magnetic stabilizing material is processed on the first surface to form a first surface film, the permanent magnet substrate is turned over by 180 degrees to the second surface, and then the second surface film is processed to form the second surface film.

In a possible implementation manner of the first aspect, the thickness variation or the concentration variation of the second side film in the distribution along the first direction is identical or identical to the thickness variation or the concentration variation of the first side film in the distribution along the first direction.

In this possible implementation manner, the fact that the film thickness of the second-side film is consistent with the thickness variation of the film thickness of the first-side film in the first direction means that the variation position, variation trend or variation amplitude of the film thickness at the position where the first side and the second side are opposite to each other is corresponding. For example, if the first side film has a film thickness at the first side position 1 that is greater than the film thickness at the first side position 2, the second side film has a film thickness at the second side position corresponding to the first side position 1 that is greater than the film thickness at the second side position corresponding to the second side position 2. The same thickness variation means that the variation position, variation trend or variation amplitude of the film thickness on the first side and the second side are the same. The concentration of the heavy rare earth element in the second surface film is consistent with the concentration change of the heavy rare earth element in the first direction in the first surface film, which means that the change position, the change trend, or the change amplitude of the concentration of the heavy rare earth element at the position where the first surface and the second surface are opposite to each other is consistent, and it can also be understood that the concentration of the heavy rare earth element is correspondingly greater in the first surface film at the position 1 than in the position 2, for example, the concentration of the heavy rare earth element is greater in the second surface film at the position corresponding to the position 1 than in the position corresponding to the position 2. The concentration variation is the same, which means that the variation position, variation trend or variation amplitude of the concentration of the heavy rare earth element on the first face and the second face are the same. According to the possible implementation mode, the thickness change or the concentration change of the films on the first surface and the second surface are consistent or the same, so that the concentration of heavy rare earth elements in the obtained magnetic stabilization permanent magnet is basically distributed symmetrically along the central line of the length direction, and the improvement of the overall coercive force of the magnetic stabilization permanent magnet is facilitated.

In a possible implementation manner of the first aspect, the distance between the first surface and the second surface is H, and H is less than or equal to 10 mm.

The height H of the magnetization direction is less than or equal to 10 mm, which is more favorable for the heavy rare earth elements to diffuse to the center of the permanent magnet substrate when the film is diffused.

In a possible implementation manner of the first aspect, the content of the heavy rare earth element in the permanent magnet base material is zero.

In this possible implementation, the permanent magnet substrate may be a zero-rare-earth substrate, that is, the permanent magnet substrate does not contain heavy rare-earth elements, so that the cost of the permanent magnet substrate can be reduced.

In a possible implementation manner of the first aspect, the magnetic stabilizing material is a simple metal substance, and the simple metal substance includes at least one of dysprosium Dy element or terbium Tb element.

In a possible implementation manner of the first aspect, the magnetic stabilizing material is an alloy, and the alloy includes at least one of dysprosium Dy element or terbium Tb element, and at least one of the following elements: copper Cu, cobalt Co, aluminum Al, calcium Ga, niobium Nb, titanium Ti, vanadium V, molybdenum Mo, and silicon Si.

In a possible implementation manner of the first aspect, the magnetic stabilizing material is a slurry, and the slurry includes at least one of a compound containing dysprosium element or a compound containing terbium element, and an organic solvent; the dysprosium-containing compound comprises at least one of dysprosium fluoride, dysprosium oxide or dysprosium hydride; the terbium element-containing compound includes at least one of terbium fluoride, terbium oxide or terbium hydride, and the organic solvent includes at least one of an alcohol solvent, a ketone solvent or an ester solvent.

In a possible implementation manner of the first aspect, the alloy composition of the permanent magnet base material includes a rare earth metal RE, iron Fe, boron B, or a transition metal M, where RE is at least one of the following elements: nd, Pr, Dy, La, Ce, Y, Ho, Tb or Gd; m is at least one of the following elements: cobalt Co, copper Cu, niobium Nb, calcium Ga, aluminum Al, zinc Zn, nickel Ni, silicon Si, zirconium Zr, molybdenum Mo, vanadium V or titanium Ti.

The second aspect of the present application provides a magnetism-stabilizing permanent magnet including a magnet having one magnetization direction, the magnetism-stabilizing permanent magnet containing therein heavy rare earth elements dispersed therein and having different concentrations in a direction perpendicular to the magnetization direction.

In the second aspect, the permanent magnet can be applied to the fields of new energy automobiles, wind power generation, energy-saving household appliances, intelligent manufacturing and the like. The permanent magnet can be a neodymium iron boron permanent magnet, the permanent magnet has a magnetization direction, a first surface and a second surface which are perpendicular to the magnetization direction are opposite surfaces, and the first surface and the second surface are also two surfaces which are parallel to each other generally. Taking a permanent magnet of a rectangular parallelepiped structure as an example, the magnetization direction is generally the direction of height, and the first and second faces are generally the upper and lower faces of the rectangular parallelepiped. Taking the permanent magnet of a pancake cylinder structure as an example, the magnetization direction is also the direction of height, and the first and second faces are usually the upper and lower surfaces of the pancake cylinder. The heavy rare earth elements can comprise elements such as dysprosium Dy or terbium Tb. In the magnetism-stabilized permanent magnet, the heavy rare earth elements have different concentration distributions along the direction perpendicular to the magnetization direction, and the concentration of the heavy rare earth elements in different regions in any parallel plane parallel to the first surface and the second surface is not all the same, so that the demagnetization resistance requirements of the permanent magnet in different position differentiation can be met.

In one possible implementation manner of the second aspect, the concentration of the heavy rare earth element in the direction perpendicular to the magnetization direction of the magnetism-stabilizing permanent magnet is first decreased and then increased. It is also understood that the concentration of the heavy rare earth element decreases and then increases in any one of the parallel planes from one end to the other end of the parallel plane along a first direction, which is a direction perpendicular to the magnetization direction in the parallel plane.

In this possible implementation manner, the first direction is a direction perpendicular to the magnetization direction, and taking the permanent magnet substrate of a rectangular parallelepiped structure as an example, the direction perpendicular to the magnetization direction may be a length direction or a width direction of the rectangular parallelepiped. The concentration of the heavy rare earth element is decreased first and then increased, and the concentration of the heavy rare earth element may be decreased in an equal proportion and then increased in a gradient manner, or may be decreased continuously and then increased. The inflection point from the lowering to the rising is generally a centerline of the parallel plane, and it can be understood that the concentration of the heavy rare earth element is a tendency of decreasing in a gradient from one end of the parallel plane to the centerline, and the concentration of the heavy rare earth element is a tendency of increasing in a gradient from the centerline to the other end. Therefore, the concentration of the heavy rare earth elements on the parallel surface is large at two sides and small in the middle, the coercive force corresponds to the concentration of the heavy rare earth elements, and the concentration of the heavy rare earth elements on the parallel surface is also large at two sides and small in the middle, so that the requirements of large demagnetization resistance at the edges and small demagnetization resistance at the center of the steady magnetic permanent magnet can be just met.

In one possible implementation manner of the second aspect, the concentration of the heavy rare earth element in the middle portion of the magnetism-stabilizing permanent magnet is lower than that in the two end regions in the direction perpendicular to the magnetization direction.

In one possible implementation manner of the second aspect, the heavy rare earth element includes at least one of dysprosium Dy element or terbium Tb element.

In one possible implementation manner of the second aspect, the heavy rare earth element includes at least one of Dy element or terbium Tb element, and at least one of the following elements: copper Cu, cobalt Co, aluminum Al, calcium Ga, niobium Nb, titanium Ti, vanadium V, molybdenum Mo or silicon Si.

In a possible implementation manner of the second aspect, the magnetism stabilizing permanent magnet has a first surface and a second surface perpendicular to the magnetization direction, the first surface and the second surface are respectively located on two opposite sides of the magnetism stabilizing permanent magnet, the distance between the first surface and the second surface is H, and H is less than or equal to 10 mm.

In the possible realization mode, the height H of the magnetization direction is less than or equal to 10 mm, so that heavy rare earth elements can be more favorably diffused to the center of the permanent magnet substrate during film diffusion.

In one possible implementation of the second aspect, H ≦ 5 mm.

In the possible realization mode, the height of the magnetization direction is less than or equal to 5mm, which is beneficial to saving heavy rare earth elements.

A third aspect of the present application provides a permanent magnet motor comprising: a rotor and a stator; the rotor comprises a rotor core and a magnetic stabilizing permanent magnet inserted into the slot of the rotor core, wherein the magnetic stabilizing permanent magnet is the magnetic stabilizing permanent magnet described in the second aspect or any possible implementation manner of the second aspect.

Drawings

FIG. 1 is a schematic diagram of an embodiment of a method for stabilizing the magnetic properties of a permanent magnet provided in an embodiment of the present application;

fig. 2 is a schematic structural diagram of a permanent magnetic substrate provided in an embodiment of the present application;

FIG. 3 is a schematic diagram of an example of a method for stabilizing the magnetic properties of a permanent magnet according to an embodiment of the present disclosure;

FIG. 4 is another exemplary diagram of a method for stabilizing the magnetic properties of a permanent magnet according to an embodiment of the present disclosure;

FIG. 5 is another exemplary diagram of a method for stabilizing the magnetic properties of a permanent magnet according to an embodiment of the present disclosure;

FIG. 6 is another exemplary diagram of a method for stabilizing the magnetic properties of a permanent magnet according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of another example of a method for stabilizing the magnetic properties of a permanent magnet provided by an embodiment of the present application;

FIG. 8 is a schematic diagram of a concentration distribution of a steady magnetic permanent magnet provided by an embodiment of the present application;

FIG. 9 is a diagram illustrating a comparison of coercivity design and test results provided by an embodiment of the present application;

fig. 10 is another comparison diagram of the coercivity design and test results provided in the embodiments of the present application.

Detailed Description

The embodiment of the application provides a permanent magnet, a magnetism stabilizing permanent magnet and a permanent magnet motor, which can improve the overall coercive force of the permanent magnet by using less Heavy Rare Earth (HRE) elements. The following are detailed below.

In the description and claims of the present application and in the above-described drawings, the terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein.

The permanent magnet is widely applied to the fields of new energy automobiles, wind power generation, energy-saving household appliances, intelligent manufacturing and the like. If a permanent magnet motor in a new energy automobile needs to include a permanent magnet, a magnetic stabilization method of the permanent magnet, a magnetic stabilization permanent magnet and the permanent magnet motor provided by the embodiment of the application are introduced below.

Fig. 1 is a schematic diagram of an embodiment of a method for stabilizing magnetic properties of a permanent magnet according to an embodiment of the present application.

As shown in fig. 1, an embodiment of a method for stabilizing magnetic properties of a permanent magnet provided by the present application includes:

101. a permanent magnet substrate is provided.

This permanent magnetism substrate includes a plurality of faces and a magnetization direction, includes first face and second face in a plurality of faces, and first face and second face are the opposite face perpendicular with the magnetization direction, promptly, first face and second face are located the relative both sides of permanent magnetism substrate respectively.

The permanent magnet substrate is exemplified by a neodymium iron boron substrate, and may be other substrates similar to neodymium iron boron materials.

The neodymium iron boron substrate can be prepared by a sintering process, the average grain size can be 1-10 micrometers (mum), and the coercive force is usually more than or equal to 1410 (kiloamperes/meter) kA/m. Coercivity (coercive force) is an index used for evaluating the quality of a permanent magnet, and means that after saturation magnetization of a magnetic material, the magnetic induction intensity B of the magnetic material does not return to zero when an external magnetic field returns to zero, and the magnetic induction intensity can return to zero only by adding a magnetic field with a certain size in the direction opposite to the original magnetization field, and the magnetic field is called a coercive field and is also called coercive force.

After the sintering process, the neodymium iron boron substrate can be processed into a block-shaped substrate, and the processed block-shaped substrate is subjected to alkali washing, acid washing, deionized water washing and drying, and can be used as a permanent magnet substrate in the embodiment of the application. The permanent magnet substrate according to the embodiment of the present invention can be understood by referring to the structure shown in fig. 2, as shown in fig. 2, the length of the rectangular parallelepiped permanent magnet substrate is L1, the width thereof is L2, and the height thereof is H. In the rectangular parallelepiped permanent magnet base material shown in fig. 2, a direction of a height (H) from bottom to top may be a magnetization direction 10 of the permanent magnet base material, and an upper surface and a lower surface perpendicular to the height may be a first surface 20 and a second surface 30, respectively.

Optionally, the content of heavy rare earth elements in the permanent magnet base material is zero. Such a substrate may also be referred to as a zero rare earth substrate, i.e. the permanent magnet substrate does not contain heavy rare earth elements, which may reduce the cost of the permanent magnet substrate.

102. A magnetic stabilizing material is provided.

The magnetic stabilizing material contains a Heavy Rare Earth (HRE) element.

The magnetic stabilizing material can be a metal simple substance, an alloy, or a slurry formed by mixing a compound containing heavy rare earth elements and an organic solvent.

The magnetic stabilizing material is a metal simple substance, and the metal simple substance comprises at least one of dysprosium Dy element or terbium Tb element.

The magnetic stabilizing material is an alloy, and the alloy comprises at least one of dysprosium Dy element or terbium Tb element and at least one of the following elements: copper Cu, cobalt Co, aluminum Al, calcium Ga, niobium Nb, titanium Ti, vanadium V, molybdenum Mo or silicon Si.

The magnetic stabilizing material is slurry which comprises at least one of a compound containing dysprosium element or a compound containing terbium element and an organic solvent. The dysprosium-containing compound comprises at least one of dysprosium fluoride, dysprosium oxide or dysprosium hydride; the terbium element-containing compound includes at least one of terbium fluoride, terbium oxide or terbium hydride, and the organic solvent includes at least one of an alcohol solvent, a ketone solvent or an ester solvent.

The method for making the slurry containing terbium element may be: raw materials for preparation such as terbium fluoride powder, ethyl acetate and solvent gum are mixed and then stirred, so that a slurry containing terbium element can be obtained. Where the terbium fluoride powder may have an average particle size of 5 micrometers (um), the weight of ethyl acetate may be several times the weight of the terbium fluoride powder, for example: the concentration of the solvent glue may be 10 wt%, where wt% represents weight percent, 3 times. Of course, this is merely an example and the weight and concentration of the several materials may be other values.

The method for preparing the dysprosium-containing slurry can be as follows: raw materials for preparation such as dysprosium fluoride, ethyl acetate and solvent glue are mixed and then stirred, so that slurry containing dysprosium element can be obtained. Wherein, the average particle size of dysprosium fluoride powder can be 5 micrometers, the weight of ethyl acetate can be 3.5 times of that of terbium fluoride powder, and the concentration of solvent glue can be 11 wt%. Of course, this is merely an example and the weight and concentration of the several materials may be other values.

103. And processing the magnetic stabilizing material on the first surface to form a first surface film.

Wherein the first surface film is distributed on the first surface along the first direction, and the film thicknesses of different areas are not all the same, that is, the first surface film has different film thicknesses on the first surface 20 along the first direction; or, the concentrations of the heavy rare earth elements in different regions of the first surface film are not all the same, that is, the concentrations of the heavy rare earth elements are different in the first surface film in the first direction at the first surface 20; wherein the first direction is a direction perpendicular to the magnetization direction 10 on the first face 20.

The first side film has a different film thickness on the first side 20, as can be understood with reference to the schematic illustration of the permanent magnet substrate after the first side film is formed as shown in fig. 3. As shown in fig. 3, the first direction 40 may be a direction from one end of the length L1 to the other end on the first face 20. Of course, the first direction 40 is not limited to the first surface 20, and may be referred to as a first direction as long as it is the same direction. The first side film may have a different film thickness on the first side 20, as shown in fig. 3, and the film thickness may decrease and then increase along the length of the first side 20 from one end to the other, and the change may be a gradient, that is, the film thickness decreases and then increases from one end to the other. The regions between the films of different thickness shown in fig. 3 are contiguous and, in fact, may be spaced apart, with a slight spacing between the regions being easier to handle when forming the first side film and also saving in magnetic stabilizing material. The films of different thicknesses on the first film can also each be referred to as a film region, which is divided by the film thickness.

Alternatively, the first side film as shown in fig. 3 may be continuous. The specific implementation manner can be understood by referring to another schematic diagram of the permanent magnet substrate after the first-side film is formed as shown in fig. 4. As shown in fig. 4, the first surface film on the first surface 20 has the largest film thickness on both sides and the smallest film thickness at the middle position along the longitudinal direction L of the first surface 20.

The first thin film has different concentrations of heavy rare earth elements on the first surface, as shown in fig. 5, and fig. 5 is a schematic diagram of the permanent magnetic substrate after the first thin film is formed. As shown in fig. 5, the film thickness on the first side film is the same, but the first side film has different concentrations of the heavy rare earth element.

In addition, the first side film as shown in fig. 5 is continuous. Alternatively, the films of different concentrations of the heavy rare earth element on the first-side film may be each referred to as a film region divided by the concentration of the heavy rare earth element.

It should be noted that the number of the areas on the first surface in fig. 3 to fig. 5 is only an example, and actually, the number of the areas on the first surface may be determined according to requirements.

The first surface film is formed by processing on the first surface, and a physical sputtering method can be adopted, such as: the heavy rare earth elements are bombarded by the target material to form a film on the first surface of the permanent magnet base material, and the slurry can also be coated on the first surface by a chemical coating method. A thin film may also be formed on the first surface by plating, electrodeposition, or the like.

104. And carrying out diffusion treatment on the heavy rare earth element on the permanent magnet base material with the thin film formed on the first surface.

The diffusion treatment may be performed by placing the substrate in a vacuum furnace and performing a heat treatment at 900 degrees celsius for 16 hours. After the diffusion treatment, heat treatment at 450 degrees celsius for 8 hours may also be performed. Of course, the specific temperature and time are not limited to 900 degrees for 16 hours and 450 degrees for 8 hours, but may be other values as long as the diffusion treatment of the heavy rare earth element is completed.

The magnetic stabilizing permanent magnet can be obtained after the heavy rare earth element is diffused.

In the embodiment of the application, in the magnetic stabilization process of the permanent magnet, the first surface film has different film thicknesses or different concentrations of heavy rare earth elements on the first surface, so that the heavy rare earth elements in the magnetic stabilization permanent magnet obtained after the film diffusion are dispersed and have different concentrations along the direction perpendicular to the magnetization direction. This first aspect has just formed the film and has still saved heavy rare earth's use amount on the first face under the prerequisite of having satisfied the anti demagnetization demand of steady magnetism permanent magnet different position differentiation like this, has reduced the cost of steady magnetism permanent magnet, in addition, through the control to film thickness or heavy rare earth's concentration on the first face, can realize steady magnetism permanent magnet's customization as required.

The thickness of the magnetic stabilization permanent magnet obtained after the diffusion treatment is carried out by forming the first surface film on the first surface is usually smaller, and the magnetic stabilization can be carried out on some permanent magnet base materials with larger thickness by the following scheme.

After step 103, step 104 is not performed, but the permanent magnetic substrate is turned 180 ° to the second side, and then step 105 and step 106 in fig. 1 are performed.

105. And processing the magnetic stabilizing material on the second surface to form a second surface film.

The second side films have different film thicknesses in the distribution along the first direction, or the first side films have different concentrations of the heavy rare earth elements in the distribution along the first direction.

Optionally, the thickness variation or concentration variation of the second side film in the distribution along the first direction is identical or identical to the thickness variation or concentration variation of the first side film in the distribution along the first direction.

The film thickness of the second-side film is consistent with the thickness variation of the first-side film in the first direction, which means that the variation position, variation trend or variation amplitude of the film thickness at the position where the first side and the second side are opposite is corresponding, for example, the film thickness of the first-side film at the position 1 of the first side is greater than the film thickness at the position 2, and the film thickness of the second-side film at the position corresponding to the position 1 of the second side is greater than the film thickness at the position corresponding to the position 2 of the second side. The same thickness variation means that the variation position, variation trend or variation amplitude of the film thickness on the first side and the second side are the same. The concentration of the heavy rare earth element in the second surface film is consistent with the concentration change of the heavy rare earth element in the first direction in the first surface film, which means that the change position, the change trend, or the change amplitude of the concentration of the heavy rare earth element at the position where the first surface and the second surface are opposite to each other is consistent, and it can also be understood that the concentration of the heavy rare earth element is correspondingly greater in the first surface film at the position 1 than in the position 2, for example, the concentration of the heavy rare earth element is greater in the second surface film at the position corresponding to the position 1 than in the position corresponding to the position 2. The concentration variation is the same, which means that the variation position, variation trend or variation amplitude of the concentration of the heavy rare earth element on the first face and the second face are the same.

In a specific implementation, the uniform thickness variation on the first surface and the second surface may be that the thicknesses of the films on the first surface and the second surface are symmetrical with respect to the permanent magnetic substrate, as shown in fig. 6, the thickness of the film decreases in a gradient from two sides to the middle of the second surface 30 in the length direction, and the gradient variation trend, the variation position, and the variation amplitude of the film on the second surface are substantially the same as those of the film on the first surface. The film thickness of the second side film is uniform with the film thickness of the first side film in the distribution along the first direction, which means that the film thickness is substantially the same at the position where the first side and the second side are opposed. For example: the film thickness of the film region on the first side 0-2 mm from the left end is 200 microns, and the film thickness of the film region on the second side 0-2 mm from the left end is also substantially 200 microns.

The uniform thickness variation on the first surface and the second surface means that the variation position, the variation tendency, or the variation amplitude of the concentration of the heavy rare earth element at the position where the first surface and the second surface are opposed to each other is substantially the same. Referring to fig. 7, fig. 7 is a schematic diagram of the permanent magnetic substrate after the second thin film is formed. As shown in fig. 7, the thickness of the second-side thin film is the same, but the second-side thin film has a different concentration of the heavy rare earth element. The concentration of the heavy rare earth element in each region of the second surface film is substantially equal to the concentration of the heavy rare earth element in each region of the first surface film. For example: the concentration of heavy rare earth elements in the region of the film 0-2 mm from the left end on the first side is 0.75 wt.% (wt.% means weight percent), then the concentration of heavy rare earth elements in the region of the film 0-2 mm from the left end on the second side is 0.75 wt.%.

The second side film is formed by processing on the second side, and a physical sputtering method can be adopted, such as: the heavy rare earth elements are bombarded by the target material to form a film on the second surface of the permanent magnet base material, or the slurry can be coated on the first surface and dried by a chemical coating method, and then coated on the second surface. A thin film may also be formed on the second face by electroplating, electrodeposition, or the like.

106. And carrying out diffusion treatment on the heavy rare earth elements on the permanent magnet base material with the thin films formed on the first surface and the second surface.

This step 106 is also followed by obtaining a magnetically stabilized permanent magnet.

The process of the diffusion process can be understood by referring to the corresponding contents in step 104 above.

In the embodiment of the present application, the film thickness corresponds to the concentration of the heavy rare earth element in the diffused magnetism-stabilizing permanent magnet, that is, the concentration of the heavy rare earth element at the corresponding position in the magnetism-stabilizing permanent magnet corresponding to the region with a large film thickness after diffusion is large, and the concentration of the heavy rare earth element at the corresponding position in the magnetism-stabilizing permanent magnet corresponding to the region with a small film thickness after diffusion is small. Similarly, in the first surface and the second surface, the region with the high concentration of the heavy rare earth element before diffusion has the high concentration of the heavy rare earth element at the corresponding position in the magnetism-stabilizing permanent magnet corresponding to the region after diffusion, and conversely, the region with the low concentration of the heavy rare earth element before diffusion has the low concentration of the heavy rare earth element at the corresponding position in the magnetism-stabilizing permanent magnet corresponding to the region after diffusion. Taking the case of the thin film thickness on both sides and then the gradient of the thin film thickness as an example similar to that shown in fig. 6, or taking the case of the thin film thickness on both sides being large and then the gradient of the heavy rare earth element concentration as an example similar to that shown in fig. 7, the concentration of the heavy rare earth element in the magnetism stabilizing permanent magnet after diffusion can be understood with reference to fig. 8. As shown in fig. 8, in any parallel plane parallel to the first surface 20 and the second surface 30 of the magnetism stabilizing permanent magnet, along the direction of the length L1, from one end to the other end (which may also be called as from the left side to the right side) of the permanent magnet, the concentration of the heavy rare earth element also changes according to the trend of descending gradient and then ascending gradient, and the trend of arrangement of the film thickness during the magnetism stabilizing process is consistent, or the trend of change of the concentration of the heavy rare earth element in the films of the first surface and the second surface is consistent.

In the embodiment of the application, in the process of stabilizing the magnetism of the permanent magnet, different areas on the first surface film and the second surface film have different film thicknesses or different concentrations of heavy rare earth elements, the film is diffused to obtain the concentration of the heavy rare earth elements in the magnet-stabilizing permanent magnet, the concentration of the heavy rare earth elements in the different areas corresponds to the film thicknesses or the concentrations of the heavy rare earth elements on the first surface and the second surface, and the coercive force of the magnet-stabilizing permanent magnet corresponds to the concentration of the heavy rare earth elements in the magnet-stabilizing permanent magnet, so that under the premise of meeting the requirement of demagnetization resistance of different positions of the magnet-stabilizing permanent magnet, because all surfaces are not required to form films containing the heavy rare earth elements, the use amount of the heavy rare earth elements is also saved, the cost of the magnet-stabilizing permanent magnet is reduced, in addition, the magnet-stabilizing permanent magnets with different concentration distributions can be obtained by controlling the film thicknesses or the concentrations of the heavy rare earth elements on, thereby realizing the customization of the steady magnetic permanent magnet according to the requirement.

It should be noted that, in the embodiments of the present application, different film thicknesses or different concentrations of the heavy rare earth elements may be different from each other, or may not be completely the same; not identical means that the film thickness may be the same over some areas, for example: in fig. 3, the film thickness may be the same in the symmetrical regions at both ends in the length direction of L1 on the first surface 20, and similarly, the concentration of the heavy rare earth element may be the same in the symmetrical regions at both ends in the length direction of L1 on the first surface 20.

Alternatively, on the first face, the film thickness of the first face film first decreases and then increases from one end of the first face to the other end along the first direction.

The concentration of the heavy rare earth element in the first surface film is generally the same, and the film thickness in different areas decreases first and then increases, either by an equal proportion of gradient decrease and then gradient increase, or by a continuous decrease and then increase. The inflection point from decreasing to increasing is generally the centerline of the first face, and is understood to mean the tendency of the film thickness to decrease in a gradient from one end of the first face to the centerline and to increase in a gradient from the centerline to the other end. When the second-side film is formed on the first side, the film thickness on the second side is substantially the same as the film thickness on the first side in the variation tendency, and the position of the variation and the magnitude of the variation are also substantially the same. Therefore, after the first surface film and the second surface film are diffused into the magnetism-stabilizing permanent magnet, the concentration of the heavy rare earth element on any parallel surface in the magnetism-stabilizing permanent magnet, which is parallel to the first surface and the second surface, is large at two sides and small in the middle, the coercive force corresponds to the concentration of the heavy rare earth element, and is also large at two sides and small in the middle, and the manufacturing requirements of high coercive force in the edge area and low coercive force in the central area of the magnetism-stabilizing permanent magnet can be just met. This scheme can be understood by referring to the corresponding contents of fig. 3, 4 and 6 described above.

Alternatively, on the first surface, the concentration of the heavy rare earth element in the thin film of the first surface decreases and then increases from one end to the other end of the first surface along the first direction.

The film thickness of the first surface film can be the same, but different areas of the first surface film have different concentrations of the heavy rare earth element, and the concentrations of the heavy rare earth element in different areas of the first surface film are reduced first and then increased, and can be reduced in an equal proportion and then increased in a gradient manner, or can be reduced continuously and then increased. The inflection point from the lowering to the rising is generally a centerline of the first face, and it is understood that the concentration of the heavy rare earth element is a tendency of decreasing in a gradient from one end of the first face to the centerline, and the concentration of the heavy rare earth element is a tendency of increasing in a gradient from the centerline to the other end. When the second-side thin film is formed on the first side, the concentration of the heavy rare earth element on the second side is substantially the same as the concentration of the heavy rare earth element on the first side in the trend of change, and the position of the change and the magnitude of the change are also substantially the same. Therefore, after the first surface film and the second surface film are diffused into the magnetism-stabilizing permanent magnet, the concentration of the heavy rare earth element on any parallel surface in the magnetism-stabilizing permanent magnet, which is parallel to the first surface and the second surface, is large at two sides and small in the middle, the coercive force corresponds to the concentration of the heavy rare earth element, and is also large at two sides and small in the middle, and the manufacturing requirements of high coercive force in the edge area and low coercive force in the central area of the magnetism-stabilizing permanent magnet can be just met. This scheme can be understood by referring to the corresponding contents of fig. 5 and 7.

Optionally, the distance between the first surface and the second surface is H, H is less than or equal to 10 mm, preferably, H is less than or equal to 5 mm. The height of the magnetization direction is limited within a certain range, which is beneficial to the diffusion of heavy rare earth elements to the center of the permanent magnet base material.

The film thickness corresponds to the concentration of the heavy rare earth element in the diffused magnetism-stabilizing permanent magnet, that is, in the area with large film thickness, the concentration of the heavy rare earth element at the corresponding position in the diffused magnetism-stabilizing permanent magnet is high, and in the area with small film thickness, the concentration of the heavy rare earth element at the corresponding position in the diffused magnetism-stabilizing permanent magnet is low. The relationship between the film thickness and the concentration of the heavy rare earth element in the diffused magnet-stabilizing permanent magnet can be understood through the following two experiments.

The first set of experiments:

the heavy rare earth element is Tb element, and in the above process of stabilizing the magnetic properties of the permanent magnetic base material, the slurry containing Tb element is coated with films of different thicknesses in different areas by a chemical coating method in a manner such as shown in fig. 6, thereby forming films of different thicknesses on the first and second surfaces, and before the diffusion process of Tb element is performed, two columns of data of the first and second columns as in table 1 below are recorded. Then, the Tb element diffusion treatment was performed, thereby obtaining a magnetically stabilized permanent magnet as shown in fig. 8. Wherein, the average particle size of terbium fluoride powder in the slurry can be 5 microns, the weight of ethyl acetate can be 3 times of that of terbium fluoride powder, and the concentration of solvent glue can be 10 wt%.

In this experimental scenario, the size of the steady magnetic permanent magnet is L1-23.5 mm, L2-28.7 mm, and H-3.2 mm. After obtaining the steady permanent magnet, a parallel surface parallel to the first surface and the second surface may be cut, and the parallel surface may have a certain thickness, for example: 0.5 mm. After switching the parallel planes, the weight percent (wt%) of Tb element was measured for the seven sample points at the positions indicated by the data in the first column, resulting in the data in the third column of table 1.

Table 1: experimental data of Tb element

Of the seven sampling points in table 1, the sampling point at 11.75mm is located at the center line position of the parallel plane, the sampling point is located in the middle two regions with respect to the eight regions in fig. 8, and the three sampling points of 1mm, 2mm, and 5mm are located in the first three regions on the left side of the center line, respectively. The three sampling points 18.5mm, 21.5mm and 22.5mm are located in the rear three regions on the right side of the midline.

As can be seen from the second column of data in table 1, the film thickness on the first and second surfaces decreases and then increases from the left end of the length (L1), and after diffusion, the concentration of Tb element in the field stabilizing permanent magnet also decreases and then increases. The thickness of the film basically has the tendency of descending gradient first and then ascending gradient from left to right in the direction of L1, and the concentration of Tb element in the magnetic stabilization permanent magnet basically has the tendency of descending gradient first and then ascending gradient.

The variation trend of the concentration of the Tb element in the magnetism-stabilizing permanent magnet also reflects the variation trend of the coercive force of the magnetism-stabilizing permanent magnet, so that the magnetism-stabilizing permanent magnet can be customized according to the requirement on the coercive force. As shown in fig. 9, the customization requirement for the coercive force can be represented by a line 1, and the result of the experimental measurement of the variation trend of the coercive force of the magnetism-stabilizing permanent magnet obtained by the magnetism-stabilizing method can be represented by a line 2. Therefore, the process of stabilizing the magnetism of the permanent magnet base material can be carried out according to the customized requirement, and the magnetism-stabilizing permanent magnet meeting the customized requirement can be obtained.

Table 1 above and fig. 9 reflect experimental data for Tb element. The second set of experiments below presents experimental data for dysprosium (Dy) element by table 2 and fig. 10.

The second set of experiments:

the heavy rare earth element is a Dy element, and in the above process of stabilizing the magnetic properties of the permanent magnet substrate, a slurry containing the Dy element is coated with films of different thicknesses in different regions by a chemical coating method in a manner such as shown in fig. 6, thereby forming films of different thicknesses on the first and second faces, and before performing the diffusion process of the Dy element, two columns of data of the first and second columns in the following table 2 are recorded. Then, the Dy element was diffused to obtain a permanent magnet with stable magnetism as shown in fig. 8. Wherein, the average particle size of dysprosium fluoride powder in the slurry can be 5 micrometers, the weight of ethyl acetate can be 3.5 times of that of dysprosium fluoride powder, and the concentration of the solvent glue can be 11 wt%.

In this experimental scenario, the size of the steady magnetic permanent magnet is L1-23.5 mm, L2-28.7 mm, and H-3.2 mm. After obtaining the steady permanent magnet, a parallel surface parallel to the first surface and the second surface may be cut, and the parallel surface may have a certain thickness, for example: 0.5 mm. After switching the parallel planes, the weight percentage (wt%) of Dy element was measured for seven sampling points at the positions indicated by the data of the first column, resulting in the data of the third column in table 2.

Table 2: experimental data of Dy element

Of the seven sampling points in table 2, the sampling point at 11.75mm is located at the center line position of the parallel plane, which is located in the middle two regions with respect to the eight regions in fig. 8, and the three sampling points of 1mm, 2mm, and 5mm are located in the first three regions on the left side of the center line, respectively. The three sampling points 18.5mm, 21.5mm and 22.5mm are located in the rear three regions on the right side of the midline.

As can be seen from the second column of data in table 2, the film thickness on the first and second faces decreases and then increases from the left end of the length (L1), and after diffusion, the concentration of Dy element in the field stabilizing permanent magnet also decreases and then increases. The film thickness basically has the tendency of descending in a gradient manner and then ascending in a gradient manner from left to right in the direction of L1, and the concentration of Dy element in the magnetism-stabilizing permanent magnet also basically has the tendency of descending in a gradient manner and then ascending in a gradient manner.

The variation trend of the concentration of the Dy element in the magnet-stabilizing permanent magnet also reflects the variation trend of the coercive force of the magnet-stabilizing permanent magnet, so that the magnet-stabilizing permanent magnet can be customized according to the requirement on the coercive force. As shown in fig. 10, the customization requirement for the coercive force can be represented by a line 3, and the result of the experimental measurement of the variation trend of the coercive force of the magnetism-stabilizing permanent magnet obtained by the magnetism-stabilizing method can be represented by a line 4. Therefore, the process of stabilizing the magnetism of the permanent magnet base material can be carried out according to the customized requirement, and the magnetism-stabilizing permanent magnet meeting the customized requirement can be obtained.

The embodiment of the application also provides a magnetism-stabilizing permanent magnet, which has a magnetization direction, wherein heavy rare earth elements are contained in the magnetism-stabilizing permanent magnet, and are dispersed in the magnetism-stabilizing permanent magnet, and different concentrations are formed in the direction vertical to the magnetization direction.

The magnetism stabilizing permanent magnet may include a plurality of faces including a first face and a second face, the first face and the second face being opposite faces perpendicular to a magnetization direction, and generally, in the magnetism stabilizing permanent magnet, a concentration of a heavy rare earth element is different on any one of parallel faces parallel to the first face and the second face.

Alternatively, the concentration of the heavy rare earth element is first decreased and then increased in the direction perpendicular to the magnetization direction of the magnetism-stabilizing permanent magnet. It is also understood that the concentration of the heavy rare earth element decreases and then increases in any one of the parallel planes from one end to the other end of the parallel plane along a first direction, which is a direction perpendicular to the magnetization direction in the parallel plane.

Optionally, the concentration of the heavy rare earth element in the middle part of the magnetism-stabilizing permanent magnet is lower than that in the periphery.

Optionally, the heavy rare earth element comprises at least one of dysprosium Dy element or terbium Tb element.

Optionally, the heavy rare earth element comprises at least one of Dy element or terbium Tb element, and at least one of the following elements: copper Cu, cobalt Co, aluminum Al, calcium Ga, niobium Nb, titanium Ti, vanadium V, molybdenum Mo or silicon Si.

Optionally, the distance between the first surface and the second surface is H, H is less than or equal to 10 mm, preferably, H is less than or equal to 5 mm. The height of the magnetization direction is limited within a certain range, and the diffusion of the heavy rare earth element to the center of the base material can be facilitated.

The magnetic stabilization permanent magnet can be a magnetic stabilization permanent magnet obtained by adopting the magnetic stabilization method of the permanent magnet, and the structure and the characteristics of the magnetic stabilization permanent magnet can be understood by referring to the experimental data of fig. 8, tables 1 and 2 in the embodiment, which is not described herein again.

The embodiment of the present application further provides a permanent magnet motor, which includes: a rotor and a stator; the rotor comprises a rotor core and a magnetic stabilization permanent magnet inserted into the slot of the rotor core, wherein the magnetic stabilization permanent magnet is a permanent magnet with corresponding magnetic stabilization property prepared by adopting the magnetic stabilization method.

From the above description, in the embodiments of the present application, a continuous or discontinuous thin film is formed in a surface perpendicular to the magnetization direction along a single direction (for example, the length direction or the width direction of the rectangular parallelepiped substrate), and after diffusion, a continuous heavy rare earth concentration distribution is formed in a cross section perpendicular to the magnetization direction, so that the coercivity gradient enhancement is realized, and the application requirements are met.

In addition, because the price of the magnetism-stabilizing permanent magnet is directly related to the content of the heavy rare earth element of the permanent magnet base material, the base material of the zero heavy rare earth element can be adopted for diffusion, so that the coercive force of the edge of the magnet and the center of the magnet can be enhanced at different degrees, and the demagnetization resistant requirements of different positions of the magnet can be met under the condition of reducing the cost of the permanent magnet base material.

Furthermore, in the embodiment of the application, the film thickness of the surface of the permanent magnet base material or the concentration of the heavy rare earth element can be accurately designed according to the coercivity requirements of the motor on different positions of each permanent magnet section of the rotor, the heavy rare earth concentration distribution and the coercivity distribution which are required by design are achieved after thermal diffusion treatment, and the magnetic performance of the permanent magnet material is utilized to the maximum extent.

The permanent magnet stabilizing method, the magnet stabilizing permanent magnet and the permanent magnet motor provided in the embodiments of the present application are described in detail above, and a specific example is applied in the present application to explain the principle and the implementation manner of the present application, and the description of the above embodiments is only used to help understanding the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. A method for stabilizing the magnetic field of a permanent magnet, comprising:

providing a permanent magnet base material, wherein the permanent magnet base material comprises a plurality of surfaces and a magnetization direction, the plurality of surfaces comprise a first surface, and the first surface is perpendicular to the magnetization direction;

providing a magnetic stabilizing material, wherein the magnetic stabilizing material contains heavy rare earth elements;

processing the magnetic stabilizing material on the first surface to form a first surface film; the first surface film has different film thicknesses in a distribution along a first direction, or the first surface film has different concentrations of heavy rare earth elements in a distribution along a first direction, the first direction being one direction perpendicular to the magnetization direction; and carrying out diffusion treatment on the heavy rare earth element on the permanent magnet base material with the film formed on the first surface.

2. The method of claim 1, wherein the first surface film decreases in film thickness and then increases in film thickness along the first direction from one end of the first surface to the other end of the first surface.

3. The method according to claim 1, wherein the concentration of the heavy rare earth element in the first surface thin film decreases and then increases from one end of the first surface to the other end along the first direction on the first surface.

4. A method according to any one of claims 1 to 3, wherein the first surface thin film is divided into a plurality of thin film regions on the first surface according to the film thickness or the concentration of the heavy rare earth element, wherein the plurality of thin film regions differ in film thickness or the plurality of thin film regions differ in the concentration of the heavy rare earth element.

5. A method according to any one of claims 1 to 4, wherein the thickness of the first thin film in the middle portion is lower than that in the two end regions along the first direction, or the concentration of the heavy rare earth element in the middle portion is lower than that in the two end regions.

6. The method of any of claims 1-5, further comprising a second surface of the plurality of surfaces, the second surface being perpendicular to the magnetization direction and the second surface and the first surface being on opposite sides of the permanent magnetic substrate, respectively, the method further comprising:

treating the magnetic stabilizing material on the second side to form a second side film having a different film thickness in a distribution along the first direction, or having a different concentration of the heavy rare earth element in the distribution along the first direction,

and carrying out diffusion treatment on the heavy rare earth element on the permanent magnet base material on which the film is formed on the second surface.

7. The method according to claim 6, wherein the thickness variation or concentration variation of the second surface film in the distribution along the first direction is identical or the same as the thickness variation or concentration variation of the first surface film in the distribution along the first direction.

8. A method according to claim 6 or 7, wherein the distance between the first and second surfaces is H, wherein H is less than or equal to 10 mm.

9. A method for stabilizing magnetic flux according to any one of claims 1 to 8, wherein the content of heavy rare earth elements in the permanent magnetic matrix is zero.

10. The method according to any one of claims 1 to 9, wherein the magnetic stabilizing material is a simple metal, and the simple metal comprises at least one of dysprosium Dy element or terbium Tb element.

11. A method according to any one of claims 1 to 9, wherein the magnetic stabilizing material is an alloy comprising at least one of dysprosium Dy element or terbium Tb element, and at least one of the following elements: copper Cu, cobalt Co, aluminum Al, calcium Ga, niobium Nb, titanium Ti, vanadium V, molybdenum Mo or silicon Si.

12. The method according to any one of claims 1 to 8, wherein the magnetic stabilizing material is a slurry comprising at least one of a compound containing dysprosium element or a compound containing terbium element, and an organic solvent;

the dysprosium-containing compound comprises at least one of dysprosium fluoride, dysprosium oxide or dysprosium hydride;

the terbium element-containing compound comprises at least one of terbium fluoride, terbium oxide or terbium hydride.

13. A magnetism-stabilizing permanent magnet characterized in that it has one magnetization direction, and that it contains heavy rare earth elements, wherein the heavy rare earth elements are dispersed in the magnetism-stabilizing permanent magnet and have different concentrations in a direction perpendicular to the magnetization direction.

14. The magnet-stabilizing permanent magnet according to claim 13, wherein the concentration of said heavy rare earth element decreases and then increases in a direction perpendicular to the magnetization direction.

15. The magnetism-stabilizing permanent magnet according to claim 13 or 14, characterized in that the concentration of the heavy rare earth element in the middle portion is lower than in both end regions in the direction perpendicular to the magnetization direction.

16. A magnetically stabilized permanent magnet according to any of claims 13-15, characterized in that said heavy rare earth element comprises at least one of dysprosium Dy element or terbium Tb element.

17. A magnetically stabilized permanent magnet according to any of claims 13-15, characterized in that said heavy rare earth elements comprise at least one of Dy element or terbium Tb element, and at least one of the following elements: copper Cu, cobalt Co, aluminum Al, calcium Ga, niobium Nb, titanium Ti, vanadium V, molybdenum Mo or silicon Si.

18. The magnet-stabilizing permanent magnet according to any one of claims 13-17, wherein the magnet-stabilizing permanent magnet has a first face and a second face perpendicular to the magnetization direction, and the first face and the second face are respectively located on two opposite sides of the magnet-stabilizing permanent magnet, and the distance between the first face and the second face is H, and H is less than or equal to 10 mm.

19. A permanent magnet electric machine, comprising: a rotor and a stator; wherein the content of the first and second substances,

the rotor comprises a rotor core and a magnetic stabilizing permanent magnet inserted into the rotor core slot, wherein the magnetic stabilizing permanent magnet is the magnetic stabilizing permanent magnet according to any one of claims 13 to 18.